In practically all of the weapons currently in existence, the cartridge must be housed in the chamber before it is possible to open fire. Thus, in terms of safety, the existence of the cartridge in the chamber is the most critical situation, since having a cartridge housed in the chamber makes it possible to immediately open fire.
The weapon user is always responsible for knowing the state of the weapon chamber. Uncertainty about the existence of a cartridge in the chamber inherently entails lack of safety and can lead to serious accidents.
Some of the most widely used weapons incorporate mechanical indicators visible from the shooting position that inform of the chamber situation. However, in conditions when light is lacking it may be difficult to determine the presence of a cartridge in the chamber by observing said mechanical indicators, so that the uncertainty associated with the presence or non-presence of a cartridge in the chamber entails even greater risks than the uncertainty itself.
Systems are known in the state of the art that make it possible to control an electric weapon detecting the presence of a cartridge in the chamber, where said systems have means to, through a supply voltage, determine the impedance of a cartridge in two possible states of the system, when there is no cartridge in the chamber and when there is a cartridge in the chamber, making use of two plates.
The previous systems include that disclosed in patent U.S. Pat. No. 5,755,056 A relating to an electronic weapon and to the process to control said weapon, where the plates are positioned to electrically contact with conductive portions of the ammunition cartridge, means to supply current to at least one of the plates, means to measure the resistance between the plates and means to compare the resistance measured with at least one reference.
The system disclosed in the previous patent comprises a comparator circuit to detect the presence of a cartridge, and in particular to detect ammunition which may be electrically fired. The circuit is formed by the contacts between the plates and a cartridge. If there is a cartridge between the two plates, the current of one of the plates is transmitted, which may be a firing pin, through the cartridge, to the second plate which may be the weapon barrel.
However, the measurement of the impedance may be affected by the user's presence, since the measurement may be distorted depending on whether the user comes into contact with metal parts of the weapon or not.
The cartridge-in-chamber detection system for firearms of the present invention has a configuration which makes it possible to resolve all the aforementioned drawbacks, providing a system which is independent of the situation where the user comes into contact with metal parts of the weapon or not.